A battery has a characteristic in an easy application according to a product group, excellent preservability, a high energy density, and the like. Further, the battery attracts attention as an energy source for improving an environmentally-friendly characteristic and energy efficiency in that a by-product according to the use of energy is not generated, as well as a primary advantage in that it is possible to decrease the use of fossil fuel.
Because of this, the battery is universally applied to a portable device, an electric vehicle (EV), and an energy storage system (ESS), and the like, and serves as a basis in various industries and simultaneously provide convenience to everyday life.
However, the battery may be abnormally driven according to a usage environment, and for example, when a battery is overcharged or a lifetime of the battery is exhausted, a swelling phenomenon and the like of the battery may be caused due to an electrical and chemical action generated inside the battery.
The swelling phenomenon of the battery may lead to an accident, such as ignition and explosion, as well as shortening of the lifetime of the battery and a decrease in capacity of the battery, so that there is a demand for a stable usage of the battery through careful monitoring and an appropriate control.
Accordingly, various research and development related to a detection of a swelling phenomenon of the battery and a protection of the battery has been conducted, and for example, a technology for detecting a change in a volume of a battery cell according to swelling by using a pressure measuring means and blocking a current through the detection has been publicly known.
However, a physical volume expansion of the battery cell is generated only when the swelling of the battery cell considerably progresses, so that it is difficult to detect and respond to the swelling phenomenon of the battery cell at an early stage, and even though a current is blocked, there is a large risk of ignition due to the considerable progress of the swelling.
As another example, a technology of blocking a current by fracturing a member, such as a bus bar and a tap, by expansive force of the battery cell by the swelling phenomenon is also present.
However, it is not easy for the technology to respond to the swelling phenomenon of the battery cell at an early stage, and spark generable during the fracturing of some of the members may act as ignition sources, thereby causing another reason for ignition.